PROJECT SUMMARY/ABSTRACT Severe aortic valve stenosis and coronary artery disease afflict a large number of patients worldwide. Choosing the optimal management strategies among various alternatives requires accounting for the characteristics and comorbidities of individuals that best determine the potential benefits or harms from different treatment approaches. However, randomized trials often do not collect the information necessary to inform individualized treatment decisions ? in particular, data on patient frailty is typically not captured. In this grant, we will take advantage of linkages between two trial programs, the Dual Antiplatelet Therapy Study (comparing shorter vs. longer duration of antiplatelet therapy after coronary stenting) and the US CoreValve Program (comparing surgical versus transcatheter aortic valve replacement), with data from Medicare claims as part of the NHLBI-sponsored Extending Trial-Based Evaluations of Medical Therapies Using Novel Sources of Data (EXTEND) Study to answer these additional questions. First, we will identify variables available in administrative claims that correlate with frailty among individuals undergoing aortic valve replacement or coronary artery stenting and assess whether they predict long-term adverse cardiovascular outcomes above traditional risk factors ascertained in trials. Next, we will determine whether claims-based frailty indices derived from these non-trial data can identify heterogeneous treatment effects ? i.e. treatment effects that differ between individuals based on their personal characteristics ? within the trials' randomized populations. Based on these results, we will then create and pilot the implementation of quantitative decision tools to support individualized treatment approaches for patients with aortic stenosis requiring aortic valve replacement and those who require dual antiplatelet therapy after coronary stent procedures. The results of this research will greatly enhance our understanding of whether administrative claims data can be used to augment the evaluation of patient frailty within clinical trials, and determine whether frail patients with cardiovascular disease require different treatment strategies. The results may also greatly improve the ability to identify individual patients who have the most or least to gain from different treatment approaches for two common and highly morbid cardiovascular conditions. Finally, the proposed research will help create evidence- based decision tools that can be used to support shared decision making between clinicians and patients with aortic valve stenosis and coronary artery disease.